Method and apparatus for afterburning exhaust gases



Ma 20, 1969 L. ANYDERSSON 3,444,687 METHOD-AND APPARATUS FOR AFTERBURNING EXHAUST GA ES Sheet Filed April 11, 1966 M R on mm E 6 Kn N N In. M

May 20, 1969 AND RSS' N 3,444,687

METHOD AND APPARATUS FOR AFT-ERBIVJRNING EXHAUST GASES miea'A rn 11, 1966 I I Sheet. 2 of 9 INVENTOR Lows Quinn.

May 20, 1969 L. ANDERSSON I METHOD AND APPARATUS FOR AFTERBURNING EXHAUST GASES Filed April 11, 1966 Sheet 3 of 9 Fig.4 45 45 a 20a. 47 '44 w u C 7 INVENTOR I Lnu'm Andees -w May 20, 1969 L. ANDERSSON 3,444,687

METHOD AND APPARATUS FOR AFTERBURNING EXHAUST GASES Filed April 11, 1966 vShee t 4 of 9 17 I h m u w 1 .INVENTOR Louis A uJewasm) May 20, 1969 L. ANDERSSON 3,444,687

METI IOD AND APPARATUS FOR AFTERBURNING EXHAUST GASES Filed April 11, 1966 Sheet 5 019 INVENTOR Lows Avdeassw Ma 20; 11969 L' ERSSQN 3, ,687 j METHOD AND APPARATUS FOR AETERBURNING EXHAUST GASES Filed Apfil 11/1966 Sheet 6 of 9 INVENTOR Lows A NdekSQoU y 20, 19 ANDERSSON 3,444,687 METHOD AND APPARATUS FOR AFTERBURNING EXHAUST GASES Filed April 11, 1966 Sheet 7 of 9' Fig.9

INVENTOR Auleaasou y 20, 1969 L. mosrassow 3,

METHOD AND APPARATUS FOR AFTERBURNING EXHAUST GASES Filed April 11. 1966 Sheet 8 019 INVENTOR Lows A'mlemssoa) MayZO, 1969 ANDERSSON 3,444,637 I -'METHOD AND APPARATUS FOR AFTERBURNING EXHAUST GASES Filed April 11, 1966 f Sheet A 9 of 9,

N u: m N N INVENTOR Laws A l gssu) United States Patent U.S. CI. 6030 19 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for the afterburning of exhaust gases produced in a combustion process wherein exhaust gases flowing through at least one flow channel are delivered to an afterburner located in an afterburning zone which occupies at least almost the entire flow channel cross-section. Secondary air is delivered to the afterburning zone for admixture with the exhaust gases to form a gas mixture, the exhaust gases being delivered to the afterburning zone at a temperature suflicient for ignition of the carbon monoxide in the exhaust gases in the presence of the secondary air. The amount of delivered secondary air of the gas mixture is controlled so that the temperature prevailing in the afterburning zone is above 950 C.

The present invention has reference to an improved method of afterburning exhaust gases wherein the latter are commingled with secondary air. Furthermore, this invention is also concerned with an improved apparatus for carrying out the aforementioned method.

Numerous proposals have already been made for afterburning exhaust gases with the aid of secondary air. However, at best they are only partially satisfactory and can only be used in certain special situations.

The present invention particularly concerns itself with the problem of completely, or at least to a very great extent, eliminating from exhaust gases deleterious gases and non-combusted residues or residues of combustion through afterburning, so that they are no longer harmful or disturbing in character.

The inventive method is characterized by the features that the exhaust gases are delivered to an afterburning zone which almost or completely occupies the flow crosssection, at a temperature which is sufiicient for the ignition of the carbon monoxide in the presence of secondary air, and the delivered portion of secondary air of the mixture is regulated such that the temperature in the afterburning zone is above 950 C.

The inventive apparatus for the performance of the aforesaid method is manifested by the features that, an afterburner is arranged in the exhaust gas conduit such that the mixture of exhaust gases and secondary air has a temperature at the afterburner which is above the ignition or firing point of carbon monoxide, and means are provided at the afterburner ensuring for a dosed and distributed infeed of secondary air throughout the afterburning zone so that the afterburner generates a temperature greater than 950 C.

By virtue of the high temperature obtained at the afterburning zone or the afterburner, it is possible to undertake combustion of even diificult to burn residues, so that the exhaust gases leaving the afterburner are practically free of smoke and soot, also free of noxious gases and hydrocarbons. Thus, it is possible to suppress the amount of carbon monoxide to a fraction of the quantity previously appearing during combustion processes. Furthermore, the efiiciency of the combustion 3,444,687 Patented May 20, 1969 plant or installation improves, resulting in considerable reduction of fuel consumption.

Accordingly, it is a primary object of this invention to provide an improved method of, and apparatus for, afterburning exhaust gases so that upon exhausting into the atmosphere air pollution is considerably less.

Another very important object of this invention relates to an improved method of, and apparatus for, the afterburning of exhaust gases resulting from a combustion process wherein the gases at worst only contain very small amounts of combustion residues, so that they are no longer deleterious or disturbing in character.

Still a further important object of my invention relates to an improved method of, and apparatus for, substantially complete afterburning of exhaust gases or the like so that the latter are relatively smokeless and free of air-polluting residues.

Yet an additional, but equally significant object of this invention pertains to an improved method and apparatus for the afterburning of exhaust gases resulting from a combustion process which not only results in a cleaner and reasonably smoke-free departing gas stream, but further, improves the efficiency of the combustion plant so that there is a reduction in fuel consumption.

One further object of this invention is the provision of improved apparatus for the afterburning of exhaust gases which is relatively simple and robust in construction, economical to manufacture, highly reliable in operation, requiring very little maintenance and servicing, and easy to install at a combustion plant.

Other features, objects and advantages of the invention will become apparent by reference to the following detailed description and drawings in which:

FIGURE 1 is a perspective fragmentary view, partly in cross-section, of an exhaust system or installation for a gasoline-driven two-stroke engine having three cylinders;

FIGURE 2 is a perspective fragmentary view of a different exhaust system or installation, partly in cross-section, for a multi-cylinder gasoline combustion engine, the exhaust installation being connected with an exhaust gas connecting piece or union common to all cylinders;

FIGURE 3 is an enlarged perspective view of the inventive afterburner unit;

FIGURE 4 is a fragmentary, longitudinal sectional view of a modified form of exhaust installation which is connected to a connecting piece common to all cylinders;

FIGURE 5 is a fragmentary, longitudinal sectional view, similar to FIGURE 4, of still a further construction of inventive exhaust installation, substantially viewed along the line VV of FIGURE 6;

FIGURE 6 is a cross-sectional view of the structure of FIGURE 5, taken along the line VI-VI thereof;

FIGURE 7 is a cross-sectional view of the afterburner, as viewed along the line VII-VII of FIGURE 5;

FIGURE 8 schematically illustrates an oil burner furnace provided with the inventive afterburner device;

FIGURE 9 is an enlarged top plan view of the afterburner device used in the furnace construction of FIG- URE 8, and viewed along the line IXIX thereof;

FIGURE 10 is a cross-sectional view of the afterburner device depicted in FIGURE 9, taken along the line XX thereof; and

FIGURE 11 is a cross-sectional view of the afterburner device of FIGURE 9, taken along the line XIXI thereof.

The inventive method is based upon the recognition that for faultless afterburning of exhaust gases two conditions must be maintained or present: The first condition is that the exhaust gases delivered to the afterburning zone together with the introduced secondary air must possess such a high temperature that there is available a temperature sufficient for the ignition of the carbon monoxide in the exhaust gases, that is, at least 610 C. (normal conditions). Therefore, the afterburning zone must be arranged in the exhaust gas channel or conduit in such close proximity to the primary combustion location that the temperature of the exhaust gas mixture does not fall below the aforementioned value. In so doing, it should be observed that the delivered secondary air, which is usually considerably cooler than the exhaust gases, does not reduce the temperature of the exhaust gases below the ignition temperature at which self-ignition occurs. Furthermore, measures must be taken to ensure that the secondary air is not delivered to the exhaust gases only at one or a few peripheral locations, rather should be distributed as uniformly as possible throughout the entire flow crosssection, in other words, the entire combustion zone. Only then is it possible to positively ensure for really faultless afterburning without an excess of air appearing at individual portions of the flow cross-section and/or a deficiency of air at other locations or portions thereof. In the event the mixture of carbon monoxide-containing exhaust gases secondary air has reached or exceeded its ignition temperature, then ignition and subsequent continuous afterburning takes place without external ignition.

The second of the two conditions is that the amount or portion of secondary air delivered to the afterburning zone must be regulated such that the temperature in the afterburning zone resulting from combustion is above 950 C. Preferably it should lie between 1,000 C. and 1,300 C. It should be apparent that to this end a number of difierent factors must be taken into consideration. It is of importance that the infed of secondary air does not occur in optional quantities, rather must be dosed or regulated such that the aforementioned temperatures are, in fact, attained. Only when the afterburner produces such high temperatures is it possible to completely eliminate diflicult to burn residues of combustion by such an afterburning. It is obvious that the quantity of secondary air is dependent upon numerous factors, among others, flow velocity, composition and temperature of the exhaust gases. It is advantageous if the secondary air delivered to the afterburning zone is not at room temperature, rather at a higher temperature. This can be expediently achieved if the secondary air is delivered through a heat exchanger heated by the thermal energy of the exhaust gases.

Experience has shown that with gasoline-driven engines for motor vehicles compliance with the first condition does not generally cause any great difficulty since the exhaust gases aspirated from the cylinders in the region of the engine block possess a temperature of about 800 C. to 900 C. This is also the case with two cycle engines. On the other hand, with diesel engines the exhaust gases are not as hot, additionally, possess a lower content of carbon monoxide than gasoline engines. Sometimes, the required exhaust gas temperature for igniting and burning the carbon monoxide is insufficient. Therefore, in the case of diesel engines, it is necessary to increase the exhaust gas temperature in the afterburning zone by reducing the flow cross-section for the exhaust gases forwardly of such afterburning zone, so that due to the increase in pressure there is brought about a temperature increase providing a suflicient temperature in any event for sustaining afterburning and, as a rule, bringing about complete combustion of the residues of combustion which, in the case of diesel engines, are present to an increased degree. Preferably, the reduction in cross-section between the discharge opening in the neighborhood of the valves and the afterburner amounts to about While keeping in mind the foregoing, the description of the inventive subject matter will initially be directed to the exemplary embodiment of inventive afterburner apparatus depicted in FIGURE 1 and, for illustrative purposes, described in connection with a three-cylinder twocycle combustion engine. It will be seen that there is provided a connecting flange 10 for direct connection to the engine block of a two-cycle engine and which has three openings or ports 11, 12 and 13 fitting exactly at the discharge openings of the corresponding cylinders of the engine. This connecting flange 10 is also provided with bores 14, 15 and 16 enabling it to be afiixed by screws or equivalent fastening expedients to the non-illustrated engine block. An exhaust gas connection or feed pipe 17, 18 and 19 extends through each of the ports 11, 12 and 13 respectively. An afterburner 24 is located within each of these exhaust gas connections 17, 18 and 19 in the neighborhood of the connecting flange 10, the details f the physical structure of which will be more fully described shortly. Following each of the afterburners 24, the respective exhaust gas channels 21a, formed by the connections 17, 18 and 19, are widened, as shown, to provide a respective expansion compartment 21, so that the gas yield or mixture which has increased due to the influx of secondary air does not bring about an impermissible heating of the walls of the connections due to compression. By virtue of the expansion of the exhaust gases sufficient heat is removed therefrom so that it is possible to lead together the subsequent pipe portions to provide a common exhaust gas conduit 26.

Concerning the physical structure of each of the afterburners 24, such incorporate a plurality of members or vanes 20 of substantially V-shaped cross-sectional configuration which are constructed as open channels 200 'at the discharge or efllux side of the gas stream. It will also be recognized that the opposed lateral ends 20d of the V- shaped vanes 20 communicate with a fresh air annulus or annular channel 8. The latter is externally bounded by a jacket or sleeve 28 which follows the contour of the exhaust gas conduit 26 so that the fresh air, i.e. secondary air is delivered towards and to the afterburners 24 in counterflow to the exhaust gases, so that heat exchange takes place.

In the case of two-stroke engines, there can be subsequently arranged in the exhaust gas conduit a non-illustrated throttling device bringing about the required counterpressure, for instance a suitable sound mufiiler.

The embodiment of apparatus depicted in FIGURE 2 is intended for motor vehicles having gasoline-driven fourstroke combustion engines. Insofar as function is concerned, this arrangement corresponds to that of FIGURE 1, with the difference that here only a single exhaust gas connection or conduit is provided in which there is located only a single afterburner 24. Exhaust gases from four-cycle combustion engines possess such a high temperature that the required temperature for ignition of the carbon monoxide is even available at some distance from the individual cylinders. It is for this reason that the exhaust gas connections connected to the individual cylinders can be brought together into a common manifold or conduit, namely to the so-called exhaust bend. This afterburning apparatus 24, according to FIGURE 2, possesses a flange 35 for connection with such non-illustrated exhaust bend. After burner 24 is arranged downstream of this flange 35 in an exhaust pipe or conduit 36. This exhaust pipe 36 widens with increasing distance from the flange 35 so that a cone or tapered socket 37 is formed in the neighborhood of the afterburner 24. Due to the increased conduit cross-section downstream of the afterburner 24 the exhaust gases expand, so that there is prevented an overheating of the V-shaped vanes 20 and the tapered socket 37 by excessive temperatures. Of course, in this instance it must also be observed that the exhaust gases delivered to the afterburner 24 are not reduced in temperature to such a degree that one is below the ignition temperature of the gas mixture of the carbon monoxide of the exhaust gases and the introduced secondary air. Introduction of secondary air is undertaken analogous to the embodiment of FIGURE 1, in that the vanes 20 of V-shaped cross-section are open at their lateral ends to provide a direct through flow connection with the annulus or ring-shaped hollow compartment 29 communicating with the annular channel 38 formed between the exhaust conduit 36 and the outer tubular sleeve or shell 40. In this manner, it is also possible in this instance to heat the secondary air delivered to the afterburner 24 since heat exchange occurs at the hollow compartment 38. In the standard manner a sound muffler is connected to the exhaust pipe 36.

FIGURE 3 depicts in perspective view details of an afterburning unit 24 as such is employed in the apparatus structure of FIGURES 1 and 2. It is assumed that the exhaust gases flow in the direction of the arrow A. This afterburner 24 is composed of a plurality of such parallelly arranged vanes 20 possessing a substantially V- shaped cross-sectional configuration, and which terminate in the same transverse plane with respect to the direction of gas flow. Vanes 20 are also distributed throughout approximately the entire flow-section. In the exemplary embodiment there is provided a total of five vanes 20 of this type. Quite obviously, it would be equally possible to provide a greater or smaller number of them. These members or vanes 20 are rigidly aflixed, for instance by welding, at a ring-shaped, substantially frusto-conical collar or holder 30, whereby the latter, just as the wall of the conical sleeve 37, is provided with through passage openings 25 for each member 20. It will be understood that such openings 25 are arranged at both ends of and in alignment with the V-shaped vanes 20.

The legs 20b of each vane 20 converge together at the upstream or infeed side of the afterburner and at their apex or tip 20a enclose an angle of approximately 4 to 30", preferably 6 to The height of these vanes for the depicted embodiment for such type vehicles, measured in the direction of fiow of the exhaust gases, lies between 12 millimeters and 40 millimeters, preferably between 14 millimeters and millimeters, wherein the conduit cross-section in front of the afterburner 24 amounted to 40 millimeters to 50 millimeters. Preferably such vane height amounts to one-third to two-thirds of the conduit diameter directly in front of the afterburner. The intermediate spaces 31 situated between the vanes 20 are selected to have such a width that the inner channel width, measured at the edges 33, collectively amount to 20% to 35%, preferably 25% to 31%, of the flow cross-section. In any event, the width of these intermediate compartments or spaces 31 between the vanes 20 is made wider than the largest width of these vanes 20. Moreover, it has been found desirable if the afterburner, measured from the lowermost or trailing edges 33 of the vanes 20, is at a distance of about 220 millimeters to 400 millimeters from the valves of the engine, particularly in the case of the four-stoke internal combustion engine exhaust arrangement of FIGURE 2.

Both the collar or holder as well as the vanes 20 are preferably manufactured from rustproof steel. Since they are situated in the flow path of the hot exhaust gases emanating from the engine, they are heated up by such and bring about that the secondary air is also heated by these vanes 20. The secondary air is initially delivered to the afterburner 24 transverse to the flow direction of the exhaust gases and entrained out of the vanes 20 due to the injector action, so that it is not necessary to deliver the secondary air with an overpressure to the afterburner 24. Consequently, there takes place a dosing of the secondary air as a function of the flow velocity of the exhaust gases and, furthermore, of course, as a function of the physical dimensions of the different components of the afterburner, especially the vanes.

When using long conduits for the secondary air or for other reasons, it can, however, be advantageous to deliver the secondary air with overpressure by using a pump or a blower. In this respect, it can be desirable to introduce the secondary air by a blower driven by the exhaust gases of the engine, so that the deliverable quantity of secondary air is approximately proportional to the quantity of exhaust gas, since the blower turns that much faster the quicker the engine runs. Such a physical construction forms the subject matter of my co-pending United States application, Ser. No. 541,607, filed Apr. 11, 1966, and entitled Tuned Resonance Mufiler.

The operation of the different embodiments of apparatus depicted in FIGURES 1 to 3 is as follows: The exhaust gases aspirated by the engine flow with great velocity and with a temperature of approximately 800 C. to 900 C. to the afterburner or 'afterburners 24 and arrive between the spaced vanes 20. At the open or down stream side of these vanes 20, specifically behind the trailing edges 33, there is turbulence, resulting in entrainment of the secondary air internally of these V-shaped vanes due to the injector action. The thus entrained secondary air is replaced by additional secondary air which fiows from the annulus or channel 8 or 29 via the lateral openings 25. The temperature of the gas mixture consisting of exhaust gases and fresh air must positively exceed 610 C.'to ensure that an afterburning flame occurs without the use of any external ignition and that combustion is sustained, during which carbon monoxide and eventual further combustible gaseous or solid components are burned. The combustion zone extends over the entire or almost the entire flow channel cross-section and merges with the transverse plane taken with respect to the flow direction of the gases and formed by the trailing vane edges 33. This combustion zone is relatively short and amounts to about 20 millimeters or less.

The afterburning zone produced by the combustion of the carbon monoxide generates a temperature of about 1050 C. in such four-cycle engine exhaust gases due to the addition of secondary air which, depending upon the composition of the exhaust gases, can climb to about 1300 C. depending upon the structural dimensions and design of the afterburner in question and further combustion conditions. This relatively high temperature in the afterburning zone brings about combustion of the combustible components contained in the exhaust gases, especially also the oil smoke, soot and so forth. There is thus obtained a complete or almost complete combustion of solid materials and transformation of difiicult to burn noxious or deleterious combustion products into those which are no longer harmful.

FIGURE 4 depicts a preferred embodiment of inventive apparatus for four-cycle combustion engines with multiple cylinders, as such is prefer-red for passenger vehicles. It is :to be appreciated that this apparatus functions analogous to the previously described constructions.

Insofar as physical structure is concerned, it will be recognized that the exhaust conduit or pipe 42 is concentrically encircled by a shell or sleeve 41 so that an annulus or ring-shaped intermediate compartment 52 is formed. The latter widens at the region of the afterburner 24 to provide an enlarged ring-shaped chamber of compartment 49 with which communicate the lateral openings 20d, previously considered, of the vanes 20. An inclined wall 48 of the exhaust conduit 42 internally delimits this compartment 49, which is further bounded by an annular wall 47 at the region of the afterburner 24. Externally such compartment 49 is bounded by an inclined Wall 43 of the outer shell or casing 41. This wall 43 merges with a cylindrical sleeve 44 widened at its forward end 44a, so that a sealing ring 45 can bear against such, as shown. Sealing ring 45 is fastened to an exhaust bend or manifold common for all of the cylinders, for example with the aid of a suitable clamping nut or otherwise. The construction and mode of operation of the actual afterburning unit 24 corresponds in principle to that of the previously considered embodiments, the only difference being that here the laterally arranged vanes 20 are inclined towards the longitudinal center line of the conduit or pipe portion 46 of the exhaust conduit 42, in order that there can be obtained as good laminar flow as possible, thus small flow resistance. For the same reason, the tips 20:: of these vanes 20 are not arranged on a straight line,

rather along an imaginary arched or curved surface, the longest vane being located at the center, as shown. Preferably, also the annular wall 47 widens at the region of the afterburner 24 by an amount substantially corresponding to the cross-sectional area occupied by the vanes 20. At the base line or edge 51 of the afterburner 24 there is situated an expansion compartment 53 which allows the gases to expand, to thereby limit the temperatures prevailing internally of the hollow compartment or chamber 54. The introduction of secondary air can occur by means of a suction funnel 62, of the type best shown in FIGURE 6, arranged at the region of the intermediate compartment or secondary air annulus 52 furthest from the afterburner 24. The center angle enclosed by the conical walls 48 amounts to about 90 so that gas expansion takes place to about double the volume.

In FIGURE there is depicted a variant of that shown in FIGURE 4. Here the enlarged annulus or hollow compartment 56 formed by the walls 57 and 58 possesses a somewhat slimmer form than the corresponding com-- partment 49 of FIGURE 4, since the center angle of the wall 57 is more acute or pointed than the center angle of the wall 48 of FIGURE 4. Depending upon the engine type either one or the other embodiment will be more suitable. Also in this case, the secondary air, just as with the embodiment of FIGURE 4, is delivered to the hollow secondary air annulus or compartment 60 disposed between the conduits 59 and 61 through the agency of an inlet funnel 62, the form of which is best ascertained by inspecting FIGURE 6. The compartments 49 (FIG- URE 4) and 56 (FIGURE 5) serve as buffer chambers for the secondary air. It would also be conceivable to conmeet the suction channel for the secondary air with the connecting rod-bearing housing.

FIGURE 7 depicts the afterburner as seen from below, in other words, from the downstream or discharge side for the gases. Therein illustrated vanes 20 with the parallel trailing edges 33 could also be modified such that the channel at the mouth region 66 does not extend parallel, rather externally widens somewhat in order to obtain as favorable as possible flow configuration.

The method and apparatus for the afterburning of exhaust gases is certainly not limited to use only with motor vehicles, rather can be employed in conjunction with any other combustion plants or equipment, for instance also with furnaces for heating or industrial applications. Hereinafter there will be described in conjunction with FIGURES 8 to 11 an afterheating apparatus for a central heating furnace heated by an oil burner.

FIGURE 8 schematically illustrates the overall furnace arrangement, specfically the guiding of the flue or exhaust gases wherein a flue gas channel 55 performs a number of turns. At the front of the furnace 56 there is located a conventional oil burner 57. The afterburner 24, which will be described shortly, is located in that portion of the flue gas channel 55 containing the ascending flue gases before such arrive at the stack or chimney 60. Naturally, the construction of the furnace and the flue gas guide means could be differently carried out, the representation in FIGURE 8 being given only for exemplary purposes. Instead of oil it would also be pos sible to fire solid or gaseous fuels, for instance coke, coal, wood, natural gas and so forth, only to mention a few.

FIGURE 9 is an enlarged top plan view of the afterburner 24 as such would appear when looking along the line IX--IX of FIGURE 8. In this physical manifestation of afterburner 2 4 there is provided a hollow frame 62 internally incorporating through passage openings for the exhaust gases. A number of vanes 20 are aifixed to the frame 62 and which, just as with the previous embodiments, have a substantially V-shaped cross-section, but additionally are slightly flexed in lengthwise direction to provide a weak S-form, as clearly seen from FIGURE 9, to impart a slight twist to the gas stream.

Moreover, from FIGURE 10, it is possible to clearly 8 recognize the arrangement of the relatively thin vanes 20 at the frame 62, the inner width a of the discharge or downstream opening thereof amounting to about three millimeters. The spacing b from one vane 20 to the next adjacent one is a multiple of the aforementioned inner width a, namely sixto twelve-fold, preferably about nine-fold. Frame 62 is constructed such that a hollow compartment 66 is provided internally thereof which, in cross-section, has an approximately triangular or trapezoidal configuration. Into this hollow compartment 66 there open a number of ports or openings 68 at the side neighboring the external surface wall and which communicate with the ambient air. The vanes 20 communicate with their open lateral ends with the compartment 66 so that the introduction of secondary air is possible. Connection of this afterburner unit 24 to the furnace wall 72 (FIGURE 11) is undertaken through the intermediary of at least one sleeve 74 onto which there is threaded a threaded sleeve 76, by means of which the wall 78 of the frame 62 can be fixedly clamped so that such afterburner projects into the flue gas channel in cantilever fashion.

An essential advantage of the described arrangement resides in the fact that the exhaust gases departing from the afterburner are considerably cooler than exhaust gases without afterburning, so that the construction of the chimney or stack 60 is simplified.

A further advantage of the present invention, particularly with diesel engine-driven vehicles is that the very unpleasant oil smoke can be eliminated. Consequently, diesel engines can operate in areas where such was not previously possible due to the unpleasant exhaust gases; it now being especially possible to employ diesel engines as stationary or travelling prime movers or drive, or for emergency power installations without having to fear contamination or soiling by oil smoke. Furthermore, due to the provision of an afterburning installation for furnaces, particularly for heating, the smokestack or flue can be considerably simpler and more economical to construct since the exhaust gas temperature is lower and contains practically no carbon black or soot. This is of considerable economic importance with respect to heat insulation of the Smokestack or chimney.

It is also here stressed that the inventive method and the inventive apparatus structure for the performance thereof are not limited to the described exemplary embodiments, rather can be used in conjunction with other installations in which a combustion process occurs. It would also be possible to somewhat modify the physical structure of the afterburner in that, for instance, the vanes, instead of extending in parallelism with one another, are constructed fan-shaped. However, experience has shown that the desired combustion, which is to be as complete as possible over the entire flow cross-section, can be especially well realized by employing the described parallel vane arrangement, since the uniform combustion throughout the entire cross-sectional area in such case has associated therewith the most favorable conditions.

Finally, in order to define some of the employed terminology, the following is to be noted: Under the term exhaust gases, or any similar expression, as employed herein, which are delivered to the afterburner, there should be understood those gases resulting from the primary combustion process and which contain combustible carbon monoxide as well as possible combustion residues of solid materials, for example in smoke or soot form. The term afterburning of exhaust gases is intended to Signify a combustion process which takes place with flame formation subsequent to the primary combustion process, and every type of primary combustion process is intended to be encompassed, irrespective whether combustion takes place in an engine or the like, a boiler, a gas turbine or in a jet propulsion power plant for an airplane, rocket or the like, and further, independently of the fact whether such installations are stationary, travelling, floating, or

flying, and irrespective of the fact whether the primary combustion process takes place through the burning of solid, liquid or gaseous fuels. The expression ignition point or its equivalent signifies the lowest temperature to be possessed by a combustible gas in mixture with air so that such can immediately ignite by itself. The term secondary air refers to oxygen-containing fresh air which may be preheated.

It should also be apparent that the features of the various embodiments disclosed herein can be combined individually or in groups insofar as there is no conflict when employing a feature from one embodiment with that of another.

While there is shown and described present preferred embodiments of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practised within the scope of the following claims.

What is claimed is:

1. Apparatus for the afterburning of exhaust gases resulting from a combustion process, comprising at least one exhaust conduit for the exhaust gases, at least one afterburner disposed in an afterburning zone of said exhaust conduit at a location such that a gas mixture of said exhaust gases and secondary air possesses a temperature at said afterburner which is above the ignition temperature of carbon monoxide, and means provided for said afterburner for delivering to said exhaust gases a dosed quantity of secondary air which is substantially uniformly distributed throughout the cross-section of the afterburning zone so that a temperature is generated by said afterburner which is greater than 950 C., wherein said afterburner comprises a plurality of vanes distributed throughout the flow cross-sectional area of said exhaust conduit and providing injection nozzles for delivery of secondary air to said afterburner, wherein said vanes are each constructed as channel-like members which open towards the discharge side of the afterburner, said vanes being arranged transverse to the flow direction of the exhaust gases and spaced from one another to provide a respective intermediate compartment between each two neighboring vanes, and wherein each of said vanes possesses a substantially V-shaped cross-sectional configuration having a pair of converging leg portions meeting at an apex remote from the open side of the channel-like members, said apex being directed towards the infeed side of the afterburner for the exhaust gases, said V- shaped channel-like members being further open at their opposed lateral ends to provide secondary air infeed openings, said secondary air-delivering means incorporating an air channel communicating with said secondary air infeed openings of said V-shaped channel-like members.

2. Apparatus for the afterburning of exhaust gases as defined in claim 1, wherein each of said intermediate compartments has a greater width than the largest width of each V-shaped channel-like vane.

3. Apparatus for the afterburning of exhaust gases as defined in claim 1, wherein said exhaust conduit includes a widened portion in the region of the afterburner, said widened portion being enlarged approximately by the amount of the cross-sectional area of the exhaust conduit occupied by the V-shaped channel-like vanes.

4. Apparatus for the afterburning of exhaust gases as defined in claim 1, wherein said V-shaped channel-like vanes are arranged substantially parallel to one another.

5. Apparatus for the afterburning of exhaust gases as defined in claim 1, wherein said V-shaped vanes are inclined towards the central lengthwise axis of said exhaust conduit, the apex of each of said vanes lying on an imaginary arched surface, said V-shaped vanes each having a dilferent height, the V-shaped vane of greatest height being located at the center of said plurality of V-shaped vanes.

6. Apparatus for the afterburning of exhaust gases as defined in claim 1, wherein the angle enclosed by said pair of converging leg portions of each V-shaped vane lies in the range of 4 to 30.

7. Apparatus for the afterburning of exhaust gases as defined in claim 6, wherein said angle preferably lies in the range of between 6 and 15.

8. Apparatus for the afterburning of exhaust gases as defined in claim 6, wherein the height of each V-shaped vane measured in the flow direction of the exhaust gases amounts to between one-third to two-thirds of the diameter of the exhaust conduit directly upstream of the afterburner.

9. Apparatus for the afterburning of exhaust gases as defined in claim 8, wherein the height of each of the V-shaped vanes lies between 12 and 40 millimeters.

10. Apparatus for the afterburning of exhaust gases as defined in claim 1, wherein said exhaust conduit includes a substantially frusto-conically shaped portion at the region of the afterburner which has a center angle in the range of 18 to 26, the frusto-conically shaped portion having its largest diameter toward the outlet of the apparatus.

11. Apparatus for the afterburning of exhaust gases as defined in claim 1, wherein said exhaust conduit includes a portion downstream of said afterburner providing a substantially frustoconical expansion compartment, the frusto-conical expansion compartment having its largest diameter toward the outlet of the apparatus.

12. Apparatus for the afterburning of exhaust gases as defined in claim 11, wherein said frusto-conical expansion compartment possesses about double the cross-sectional area of the preceding portion of the exhaust conduit.

13. Apparatus for the afterburning of exhaust gases as defined in claim 1, further including a jacket encircling in spaced relation at least the portion of said exhaust conduit located downstream of said afterburner to provide a preheating annulus through which secondary air flows in countercurrent to said exhaust gases.

14. Apparatus for the afterburning of exhaust gases as defined in claim 13, wherein said exhaust conduit and encircling jacket include portions cooperating with one another at the region of the afterburner to provide a widened annular chamber of said preheating annulus.

15. Apparatus for the afterburning of exhaust gases as defined in claim 1, wherein there are provided at least five V-shaped vane members which extend across the entire flow cross-section of said exhaust conduit.

16. Apparatus for the afterburning of exhaust gases resulting from a combustion process, comprising at least one exhaust conduit for the exhaust gases, at least one afterburner disposed in an afterburning zone of said exhaust conduit at a location such that a gas mixture of said exhaust gases and secondary air possesses a temperature at said afterburner which is above the ignition temperature of carbon monoxide, and means provided for said afterburner for delivering to said exhaust gases a dosed quantity of secondary air and for substantially uniformly distributing the secondary air throughout the cross-section of the afterburning zone, so that a temperature is generated by said after burner which is greater than 950 C., said afterburner comprising a plurality of vanes distributed throughout the flow cross-sectional area of said exhaust conduit and providing injection nozzles for delivery of secondary air to said afterburner, and wherein each of said vanes possesses a substantially V-shaped cross-sectional configuration and are open towards the discharge side of said afterburner, each of said V-shaped vanes being open at opposed lateral ends, said secondary air-delivering means incorporating an annular channel communicating with said lateral opposed open ends of said vanes for infeed of secondary air thereto through an injector action, said exhaust conduit incoporating means providing an expansion compartment downstream of said afterburner, said annular channel providing a heat exchanger surrounding said exhaust conduit and operating in countercurrent flow to said exhaust gases in order to pre-heat the infed secondary air, said annular channel being widened at the region of said afterburner.

17. Apparatus for the afterburning of exhaust gases as defined in claim 16, further including means for detachably connecting said exhaust conduit to a common engine manifold for a number of exhaust pipes.

18. Apparatus for the afterburning of exhaust gases as defined in claim 17, further including an internal combustion engine having valve means, the lowest point of said afterburner being disposed at a distance of about 220 to 400 millimeters from said valve means.

19. Apparatus for the after-burning of exhaust gases as defined in claim 16, wherein said exhaust conduit is throttled in cross-section upstream of said afterburner.

References Cited UNITED STATES PATENTS 2,620,967 12/ 1952 Worn. 1,897,746 2/ 1933 Winslow 60--30 2,230,666 2/1941 Martin 60-32 0 WENDELL E. BURNS, Primary Examiner.

us. 01. X.R. 181-51; 110-8 

